Typically in next generation networks data sessions are carried over pre-reserved paths, such that the establishment of a data session involves a reservation phase where resources for the session are allocated and then held for the duration of the session and are released once the session is terminated. Some examples of such networks include MPLS, Optical and ATM networks.
In general, the resource allocation for paths for the sessions of a network is performed by individual edge elements of these networks which perform this allocation under limited global network information using simple algorithms (e.g. constrained-shortest-path-first (CSPF)), thus not necessarily leading to optimal use of network resources. In addition as sessions are terminated and resources released, the current resource allocation for the remaining sessions may not stay optimal. Many of these types of networks do, however, support opportunistic re-routing where network resources are reallocated by the edge elements for the existing sessions if it leads to a better use of the resources under some measure. Unfortunately, this re-allocation is performed under limited global network information using simple algorithms (e.g., CSPF).
In other prior art schemes, powerful off-line route servers with a global knowledge of the network perform online or offline routing of the sessions of a network. These schemes, however, generally implement heavy duty machinery, such as Linear Program solvers, thus imposing a heavy burden on the underlying computational infrastructure.